Yes, i asked a question about this as well.
Currently i am ineed maintaining my own state of the graph which didnt seem handy at first, but became necessary later on, since i built my own modules, inputs/outputs and connections on top the api (and which is not a 1 to 1 copy).
But i still sthink it would be a good addition, especially since there's a new interface for the disconnect method coming up (the current one cannot in all cases remove a single connection) which will not be availbable in all browsers. So you'd end up disconnecting something and not knowing what the resulting state is, since different implementations will respond differently.
Peter